This cup is the new testament in My blood, which is shed for you.@Luke 22:20
Isaac Watts (1674–1748)

Isaac Watts, Hymns and Spiritual Songs 1709, Book III, number 3. The new testament in the blood of Christ, or, the new covenant sealed.

York. Melody from the Scottish Psalter, 1615; harmony by John Milton (1562–1647) (🔊 pdf nwc).

The promise of My Father’s love
Shall stand for ever good,

He said, and gave His soul to death,
And sealed the grace with blood.

To this dear covenant of Thy Word
I set my worthless name;
I seal th’engagement to my Lord,
And make my humble claim.

The light, and strength, and pardoning grace,
And glory shall be mine;
My life and soul, my heart and flesh,
And all my powers are Thine.

I call that legacy my own
Which Jesus did bequeath;
’Twas purchased with a dying groan,
And ratified in death.

Sweet is the memory of His name,
Who blessed us in His will,
And to His testament of love
Made His own life the seal.